Performance and Characterization of Bi-Metal Compound on Activated Carbon for Hydrogen Sulfide Removal in Biogas

This study reports on the synthesis of bi-metal compound (BMC) adsorbents based on commercial coconut activated carbon (CAC), surface-modified with metal acetate (ZnAc₂), metal oxide (ZnO), and the basic compounds potassium hydroxide (KOH) and sodium hydroxide (NaOH). The adsorbents were then characterized by scanning electron microscopy and elemental analysis, microporosity analysis through Brunauer-Emmett-Teller (BET) analysis, and thermal stability via thermogravimetric analysis. Adsorption-desorption test was conducted to determine the adsorption capacity of H₂S via 1 L adsorber and 1000 ppm H₂S balanced 49.95% for N₂ and CO₂. Characterization results revealed that the impregnated solution homogeneously covered the adsorbent surface, morphology, and properties. The adsorption test result reveals that the ZnAc₂/ZnO/CAC_B had a higher H₂S breakthrough adsorption capacity and performed at larger than 90% capability compared with a single modified adsorbent (ZnAc₂/CAC). Therefore, the synthesized BMC adsorbents have a high H₂S loading, and the abundance and low cost of CAC may lead to favorable adsorbents in H₂S captured.